肥胖儿童骨密度变化及其影响因素分析

The change of bone mineral density and its influencing factors among obese children

目的分析肥胖儿童骨密度(BMD)及其影响因素,为早期预防骨质疏松提供科学依据。方法2007年1—12月从长沙市开福区5所小学7～12岁学龄儿童中,按照体质指数(BMI)法诊断单纯性肥胖,随机抽取119例单纯性肥胖儿童及103名正常儿童。采用双能X线骨密度仪(DEXA)全身扫描,测量BMD和身体成分。结果单纯性肥胖儿童的身高、体重、BMI、腰围和腰臀比均显著高于正常儿童。单纯性肥胖儿童的各部位瘦组织含量(LM)、脂肪组织含量(FM)、体脂百分比(PBF)及躯干脂肪组织百分比均显著高于正常儿童,但四肢FM百分比却显著低于正常儿童。肥胖儿童各部位BMD和骨矿物质含量(BMC)均大于正常儿童。控制FM后,BMD(或BMC)与LM呈显著正相关:控制LM后,BMC与FM亦呈正相关。多元逐步回归分析显示,影响儿童BMD的主要因素是LM。结论肥胖儿童BMD高于正常儿童,LM对儿童成长中骨的BMD起重要作用。

Objective To study the change of bone mineral density （BMD） and its influencing factors among obese chil- dren and to provide the scientific evidence for early osteoporosis prevention.Methods Obesity was assessed by the method of body mass index（BMI） among children aged 7 to 12 years in five primary schools of Kaifu District in Chang- sha in 2007, and 119 obese subjects and 103 control subjects were randomly selected.Total-body dual-energy x-ray ab- sorptiometry （DEXA） scans were performed to obtain BMD and body composition. Results Obesity group had higher height, weight, BMI, waist circumference and waist to hip ratio as compared with those of control group. Obesity group had greater values of lean mass （LM）, fat mass （FM）, percentage of body fat and truncal FM proportion, but lower val- ues of extremity FM proportion in comparison to controls. Obesity group had higher BMD and bone mineral content （BMC） as compared with those of controls. When FM was controlled, there was positive correlation between BMD （or BMC） and LM. When LM was controlled, there was positive correlation between BMC and FM. Multiple stepwise regres- sion models indicated that LM was the dominant influencing factor of BMD in children. Conclusion The findings of this study suggest that obese children have higher BMD than controls and LM is the primary determinant of BMD in developmemt of children.